Typically, a cutting tool, in which an indexable cutting insert is mounted, is used for vertical machining of a metal workpiece. There exist in the art various cutting tools for vertical machining, in which an indexable cutting insert is mounted. Conventional cutting tool is configured such that a cutting insert is coupled to a cutter body by means of a screw. Korean Laid-Open Patent Publication No. 2006-0135212 discloses an example of such a conventional cutting tool.
Further, in a conventional cutting insert, a cutting edge for cutting is formed at a top surface, a mounting surface is formed in a bottom surface, and a hole is bored at the center of the mounting surface. In such a conventional cutting insert, a side surface of the cutting insert and the mounting surface of the bottom surface may form an obtuse angle therebetween.
Recently, in the field of metal machining, it has become an important issue to become competitive by effectively controlling the rise in production costs. Further, enhancing productivity is the key factor to becoming competitive. To enhance productivity, a feed per cutting edge during a cutting operation must be increased.
However, when machining a workpiece at a high feed rate for enhancement in productivity using the conventional cutting insert, wherein the side surface and the mounting surface of the bottom surface form an obtuse angle, the cutting force generated during machining may break the screw. It may cause not only the breakage of the screw, but also the separation of the cutting insert, the damage of the cutter body, and the damage of the workpiece, thereby leading to serious problems. The breakage and damage become more crucial in cases where reliability of cutting is important (e.g., when machining expensive parts for an aircraft).